In the electrical connector art, various terminals are known which are affixed within passageways of connector housings, each with a contact section exposed at a mating face of the connector for mating with a complementary terminal of a mating connector, and each including an elongate section extending from an opposed mounting face of the housing for insertion into a corresponding through hole of a circuit board when the connector is mounted to a surface of the board. After insertion, such elongate or pin sections are commonly soldered to conductive material plated to the side walls of the through holes or to annular pads surrounding entrances to the through holes, defining electrical connections to respective circuits of the board.
It is known for such pin sections to be configured in such a way as to define compressible spring members along the portions disposed within the through holes upon full insertion, to establish a press fit providing assured mechanical engagement directly against the plating material of the through hole which defines gas tight electrical connections. Such spring members also serve as a retention mechanism holding the connector to the board prior to the soldering operation thus obviating the need for clamps or other tooling.
One such compliant pin section is disclosed in U.S. Pat. No. 3,634,819. Several various embodiments of pin sections all include the common principle of a pair or more of leg sections spaced apart to define a portion having an effective diameter larger than the diameter of the through hole of the circuit board into which the portion is to be inserted. Upon insertion, the spaced apart leg sections are urged toward each other by the walls of the through hole, under compression with sufficient spring strength thereafter for the portion to continuously exert spring bias outwardly against the walls of the through hole after insertion. The leg sections may be formed by flattening originally round stock and then punching an elongate slot into the flattened portion, or by punching an elongate slot into originally flat stock. Another variety is disclosed wherein originally flat stock is stamped to have two or three legs joining upper and lower integral terminal portions and then gently bowing the legs out of the plane of the stock, after which the stamped blank is rolled into a cylindrical shape such that the bowed legs protrude radially outwardly and can be compressed radially inwardly upon through hole insertion. Similar compliant sections are found in U.S. Pat. Nos. 4,655,518; 4,824,380 and 5,106,328.
Another compliant pin section is disclosed in U.S. Pat. No. 3,400,358 in which a pair of outwardly bowed wire halves are welded together at both ends, for insertion of the outwardly bowed portions to be inserted into a common through hole. The facing surfaces of the wires may be flattened at least at the end sections facilitating welding.
It is also known In U.S. Pat. No. 5,004,426 to provide a pair of contacts each of planar construction adjacent each other, having adjacent pin sections for insertion into a common circuit board through hole, and having adjacent tuning fork contact sections at an opposite end for mating to a common complementary contact member, providing redundant circuit paths from the circuit board to the complementary contact. The pin sections include compliant sections each compressible during through hole insertion, said to be internally solder-coated.
In U.S. Pat. No. 4,186,982 a compliant pin section is disclosed to be defined in a solid pin portion initially having a round or square or rectangular cross-section. In one embodiment wherein the pin portion is formed from square stock, the square stock is initially sheared along a limited length axially extending slit to define a pair of leg sections, and the thus-sheared leg sections are formed transversely along the shear plane to be offset with respect to each other in the shear plane. When the offset legs are inserted in an aperture in a circuit board, as the diagonally opposed corners of the offset legs bear against the aperture walls, the offset legs are forced towards each other along the shear plane with facing sheared surfaces experiencing a strong component of force normal to the shear plane, which contributes to a strong spring-like force applied by the legs on the walls of the aperture. The force is strong enough to establish by itself a permanent gas-tight connection to the plating material without subsequent soldering for both self-sufficient mechanical and electrical connection to the board.
In U.S. Pat. Nos. 3,997,237 and 4,066,326 there is disclosed a contact including three legs, or fins, defined along two shear planes, which are pressed against and along each other upon through hole insertion. In U.S. Pat. No. 4,230,384 a compliant pin terminal is formed from flat stock to have a limited length axial slit defined therealong to form a pair of legs, with the legs then being twisted in opposed directions to define torsion members which become rotated and urged toward each other upon through hole insertion to create an interference fit.
A separate component is assembled to the pin portion of a terminal in U.S. Pat. No. 4,684,203. The component is affixed to the pin and includes a pair of opposed outwardly bowed spring arms of arcuate cross-section coextending along a length of the pin, which upon through hole insertion are urged against the pin portion therebetween and also flattened in cross-section, to generate substantial spring force outwardly against the through hole walls.
And it is also known to provide a contact stamped from flat stock of uniform thickness and formed into a tubular shape to have a compliant pin structure of tubular shape for insertion into a board through hole, in U.S. Pat. No. 4,780,958, wherein the exposed contact section is to comprise a post extending from the circuit board for wire wrapping.
Certain contacts are provided with receptacle or socket contact sections at ends opposed to the pin sections insertable into the circuit board through holes. Such receptacle contact sections can provide four spring arms arrayed about a post or pin receiving region for engaging the post of the complementary contact member on four sides, and such a structure is made by forming a box-like structure from a blank stamped from a strip of metal which of necessity must have a limited thickness to permit forming. The pin sections must be made of thicker material than that useful in forming the receptacle sections, and commonly the strip of metal is skived into halves of greatly differing thicknesses, with the receptacle half having a thickness of for example about 0.0040 inches and the pin section half having a thickness of for example about 0.025 inches.
It is desired to provide a terminal having a receptacle section formed at one end and a compliant pin section defined at the other for through hole insertion which is fabricatable from a strip of constant thickness metal.
It is further desired to provide such a terminal which provides a controlled reduction in insertion forces and yet establishes sufficient retention force following insertion to obviate any need for solder to define an assured electrical connection with the through hole plating material, thus permitting contact replacement without desoldering and resoldering.